Implementation changes

• 8-8-04: Released first version. It is an adaptation of SPIN version 4.1.1.
• 9-29-04: Fixed a bug with the BMP subset pruning. The algorithm still produced non-minimal successor configurations. Runtime on large models without counterexamples improves by about 20% (600s instead of 800s on the dinphil_i10 example)
• 10-29-04: Made LWAASpin and the resulting pan source ANSI-C compatible. It still yields a lot of warnings, but should compile on older compilers. There are still reports on linking errors on older ld versions.